This sum represents nearly 30 per cent of the £504m harm reduction target it hopes to achieve by 2015.

One of the operations conducted by the PCeU, codenamed "Pagode", involved busting an online criminal forum in which fraudsters unlawfully obtained credit card details and exchanged malware, botnets and tutorials on criminal activity. The operation prevented an estimated £84m worth of harm to the economy.

The PCeU, which was set up in 2008, is an 85-strong team that aims to combat malware, denial-of-service attacks and fraud over the internet.

The government allocated £30m to the unit in January to help fund its efforts for four years.

"In the initial six-month period the unit, together with its partners in industry and international law enforcement, has excelled in its efforts to meet this substantial commitment and has delivered in excess of £140m of financial harm reduction to the UK economy. We hope to be able to better this result in the future as we expand our national capability," said deputy assistant commissioner, Janet Williams.

Detective superintendent Charlie McMurdie of the PCeU believes that although the £504m target may be surpassed, "the figure alone does not capture the other important benefits gleaned from the learning obtained from targeting these cyber criminals and shareing information with our partners."

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